Urinary Antiseptics

Question 1

Name the Urinary Antiseptic

Answer 1

Nitrofurantoin

Question 2

Trade Names of Nitrofurantoin (Synthetic Nitrofuran)

Answer 2

Furadantin and Macrobid

Question 3

Uses of Nitrofurantoin

Answer 3

Prevention and Treatment of Lower UTI
(Acute lower UTI, Prophylaxis of lower UTI)

Question 4

Nitrofurantoin MOA

Answer 4

Nitrofurantoin sensitive bacteria reduces the drug to a highly active intermediate that inhibits various enzymes and disrupt the synthesis of proteins, DNA, RNA, metabolic processes

Question 5

Nitrofurantoin Spectrum Activity - 2 main bacteria classes?

Answer 5

E coli and Enterococci

Question 6

When is antibacterial activity higher?

Answer 6

In acidic urine (pH < 5.5)

Question 7

What species are resistant to Nitrofurantoin?

Answer 7

Proteus, Pseudomonas, Enterobacter, Klebsiella

Question 8

Administration route of nitrofurantoin and absorption kinetics?

Answer 8

Oral - Rapid (Can be slowed down if it is formulated in macrocrystalline form)

Question 9

Nitrofurantoin distribution - Why does nitrofurantoin have limited systemic exposure?

Answer 9

High urinary concentrations due to rapid clearance

Question 10

What is the advantage of nitrofurantoin distribution pharmacokinetic property?

Answer 10

Good target for urinary tract infections

Question 11

How is nitrofurantoin eliminated?

Answer 11

40% fraction excreted unchanged in the urine

Question 12

How are patients with impaired glomerular function affected in the use of nitrofurantoin for the treatment of urinary tract infections?

Answer 12

Since rate of excretion is linearly related to CrCL, decreased glomerular filtration means lower drug efficacy and increased systemic toxicity

Question 13

What does nitrofurantoin do to urine color?

Answer 13

Turns urine brown

Question 14

List some common or occasional adverse effects of nitrofurantoin

Answer 14

1. N/V/D are common (Macrocrystalline preparations are better tolerated)
2. Hypersensitivity (Chill, fever)
3. Cholestatic Jaundice and Hepatocellular damage (Nitro-reductive metabolism producing oxidative free radicals) - Rare
4. Liver injury from prolonged incubation period

Question 15

Which patient profile should we take note off for specific adverse effects?

Answer 15

1. G6PD deficiency - Leukopenia, hemolytic anemia
2. Elderly - Pulmonary Toxicity
3. Renal Impairment - Peripheral neuropathies can occur in these patients (Rare)

Question 16

What patient population should not receive nitrofurantoin and why?

Answer 16

1. Renal impairment (CrCL < 40 mL/min) - Impaired glomerular filtration affects the distribution of nitrofurantoin into the urine
2. Pregnant women - Possibility of hemolytic anemia
3. Infants < 1 month old - Possibility of hemolytic anemia